Process of making phthalic acid.



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AENT Fries,

EUGEN SAPPER, OF LUDWIGSHAFEN, GERMANY, ASSIGNOR TO THE BADISOHE ANILINAND SODA FABRIK, OF SAME PLACE;

. PROCESS or MAKING VPHT'HALIC Able.

srnclnce'rron forming part of Letters Patent K036443211, dated February27, won.

Appllcstlon llled November 16, 1897. Serial lilo 58,740. (Bpeolmena) Toall whom it may concern;

Be it known that I, EUGEN SAPPER, doctor of science, asubject of theKingof Bavaria, residing at Ludwigshafen-on-the-Rhine, in the Kingdom ofBavaria and Empire of Germany,

, have invented newand useful Improvements in the Manufacture andProduction of Pht halic Acid, (for which patents were obtained inGermany March 31,1806, No. 91,202; in 'England August 17, 1896, No.18,221; in France September 16, 1896, No. 259,766; in Belgium September28,1896, No.123,,751; in Italy September- 30, 1896, 'XXXII,.42,724,LXXXIII, 401; in Austria June 16,1897, No. 47/2344; in Hungary January30, 1897, No. 8,747, and in Spain November 21, 1896, No. 19,712,) ofwhich the following is a specification.

Myinvention consists in anew process'for the production of-phthalicacid.

The following will serve-to illustrate the manner in which the inventioncan best be carried into effect; but I do not limit my process tothisexample. The parts are by weight.

Mix together about one hundred (100) parts of naphthalene, one thousandfive hun red (1,500) parts of sulfuric acid, (mono-hydrate onehundredpercent. (100%) H 80 and fifty (50) parts of-mercnric'sulfate ard warmthe mixturetillnaphthalenedissolves. Nextheat the mixture further in aretort or other vessel suitable for distilling. As'the temperaturereaches about two hundred degrees centigrade (200 C.) the beginning ofthe reaction can be noticed, and it proceeds more rapidly at two hundredand fifty degrees-centigrade,(250 C.)

' Sulfurous acid and carbonicacid are given off by the melt. Raise thetemperature finally to three hundred degrees centigrade (300C) andhigher and maintain the heat until the contents are solid or viscous.-While heating,

.collect the distillate in a suitable receiver.

The distillate consists of suit uric acid diluted with the Water formedduring the reaction and the-phthalic acid produced partly as anhydrideand some sulfo-phthalic-acid. The

phthalic acid separates out almost completely on cooling and iscollected byfil'tering or by treatment in a centrifugal machine. Theresidue in the retort contains the mercuric sulfate, which can be usedagain in another operation.

Instead of napnthalcnein the above example there can be usedany of thefollowing aromatic substances whose nuclei consist in whole or in partof the naphthalene nucleus-- viz., sulfo-acids of naphthalene, alpha orbeta naphthol or the sulfo-acids thereof, alpha or beta napht-hylamineor the sulfo-acids ther e of, mono-nitro-naphthalene or the sulfo-acidsthereof, anthracene, phenanthrene, and instead of. mercuric sulfateitself there can be used mercury or the oxids or compounds thereofcapable of being converted into mercuric sulfate in thecourse of theprocess. Also the quantity of sulfuric acid used and its strength may bevaried within wide limits.

The following are instances of mixture which can be similarly treated:(a) one hun dred (100) parts beta-naphthol dissolved in three mndred(300) parts ofoleum, (fuming sulfuric acid,) containing about twenty percent. (20%) free sulfuric anhydride, and then added to about onethousand (1,000) parts mono-hydrate and forty (40) parts mercuricnitrate; (b) one hundred (100) parts naphthionic acid, one thousand(1,000) parts concentrated sulfuric acid, (containing about ninety toninety-five per cent. to 05%) H SO and thirty (30) parts mercuric oxid;(c) one hundred (100) parts phenanthrcne, two thousand (2,000) partsmono-hydrate sulfuric acid, and twenty (20) parts mercury.

. I employ herein the term naphthalene body to designate naphthaleneeither in its unsulfouated or sulfonated form.

Now what I claim is- 1. The process of producing phthalic acid whichconsists in heating a. substance whose formula contains that of thenaphthalene nucleus with sulfuric acid in the presence of mercuricsulfate, substantially as described.

. 2. The process of producing phthalic acid which consists in heating ahereinbefore-defined naphthalene body with sulfuric acid until phthalicacid is produced, substantially as described.

In testimony whereof I- have hereunto set I my hand in the presence oftwo subscribing witnesses.

EUGEN SAPPER.

Witnesses:

Gusrsv LICHTENBERGER, BERNHARD C. IIEssE.

